JPH0733780B2 - Engine fuel injector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel injection device for an engine, and in particular, a so-called thinned injection operation is performed by repeating a combustion cycle and a rest cycle in a predetermined synchronization in each combustion chamber. Regarding the improvement of what was done.

(Prior Art) Conventionally, as one of the technologies for improving the fuel efficiency of an engine, as disclosed in, for example, Japanese Patent Laid-Open No. 55-29002, generally, when the engine is operated under a high load condition, the fuel efficiency is improved. Therefore, the operation of some cylinders is stopped during low-load operation of the engine, and the load per unit cylinder of the remaining operating cylinders is relatively increased to improve fuel efficiency in the low-load operating range. Cylinder number control engines are well known.

On the other hand, such a cylinder number control engine is divided into cylinders that are inactive and cylinders that are operating during reduced-cylinder operation, and therefore there is a problem in terms of durability due to variations in the operating time of each cylinder. In one combustion chamber, the fuel injection and the non-injection are performed at a predetermined interval from the fuel injection valve so that the combustion cycle and the rest cycle are repeated at a predetermined cycle, that is, the alternating injection is performed to improve the fuel consumption. There has been proposed a so-called thinned-out injection type fuel injection device that solves the problem of durability. Moreover, in this thinned-out injection method, since only fresh air is supplied to the combustion chamber and discharged in the rest cycle, there is no carry-in of dilution gas into the combustion cycle after this rest cycle, and therefore low load is applied. This is effective in improving ignitability and combustibility in a region where the intake air charge amount is small, such as during operation. In particular, a rotary piston engine is suitable because the amount of dilution gas originally brought in is large due to the overlap of the intake and exhaust ports. Further, by gradually changing the thinning rate (ratio of pause cycles), there is an advantage that the thinning injection operation can be changed to the normal operation and the normal operation can be changed to the thinning injection operation without torque shock. .

(Problems to be solved by the invention) By the way, in such a thinning-out injection type, the thinning-out ratio is 1/3, 1/4, etc. When the (pause cycle) is performed, although the dilution gas is not brought in as described above in the combustion cycle after the previous pause cycle, the dilution gas is brought in as before in the combustion cycle after the previous combustion cycle. For this reason, assuming the combustion cycle after the previous pause cycle without the carry-in of dilution gas and setting the air-fuel ratio of the air-fuel mixture supplied to each combustion cycle to lean, the previous combustion with carry-in of the dilution gas is performed. In the combustion cycle after the cycle, reliable ignitability and good combustibility cannot be obtained. If the air-fuel ratio in each fuel cycle is set to rich in order to secure good ignitability and combustibility by assuming the combustion cycle after the previous combustion cycle, the original improvement in fuel efficiency will be impaired.

The present invention has been made to solve such contradictory problems, and during thinning injection operation, good ignition is achieved by changing the air-fuel ratio set in the combustion cycle after the last rest cycle and the combustion cycle after the last combustion cycle. The purpose is to reduce fuel consumption while ensuring fuel efficiency and combustibility.

(Means for Solving Problems) In order to achieve this object, in the present invention, only the air-fuel ratio in the combustion cycle after the last rest cycle is set to lean during the thinning injection operation.

Specifically, the solution means taken by the present invention includes a fuel injection valve for injecting and supplying fuel, and the fuel injection is performed so that a combustion cycle and a rest cycle are repeated at a predetermined cycle in each combustion chamber at least during low load operation. A fuel injection device for an engine that performs fuel injection from a valve and non-injection thereof at predetermined intervals. Then, on the other hand, the combustion injection valve is controlled so that the air-fuel ratio of the air-fuel mixture supplied to the combustion cycle after the last rest cycle becomes leaner than the air-fuel ratio of the air-fuel mixture supplied to the combustion cycle after the last combustion cycle. The control device is provided.

(Operation) With the above configuration, in the present invention, in the thinning injection operation, in the combustion cycle after the previous rest cycle, even if the air-fuel ratio is set to be leaner than the combustion cycle after the previous combustion cycle, the dilution gas Since there is no carry-on, fuel consumption can be reduced correspondingly without impairing ignitability and combustibility. On the other hand, in the combustion cycle after the previous combustion cycle, the air-fuel ratio is richer than that in the combustion cycle after the previous rest cycle, so good ignitability and combustibility can be secured even with the introduction of dilution gas. become.

(Example) Hereinafter, the Example of this invention is described in detail based on drawing.

FIG. 1 shows an embodiment in which the present invention is applied to a rotary piston engine, in which 1 is a rotary piston engine, which comprises a rotor housing 2 having a trochoidal inner peripheral surface and side housings 3 and 3 arranged on both sides thereof. A polygonal rotor 5 is supported by an eccentric shaft 6 and planetarily rotates in the casing 4, thereby partitioning the casing 4 into three working chambers 7, 7, 7. 7
The intake stroke, the compression stroke, the explosion stroke, the expansion stroke, and the exhaust stroke are sequentially performed, and each working chamber 7 constitutes a combustion chamber. Incidentally, 8 is an intake port, 9 is an exhaust port, and 10 and 11 are spark plugs on the leading side and the trailing side.

12, one end communicates with the intake port 8 and the other end has an air cleaner
A throttle valve 14 for controlling the amount of intake air is provided in the intake passage 12 for supplying intake air to the working chamber 7 by opening to the atmosphere through 13, and a fuel is provided downstream thereof. A combustion injection 15 for injecting and supplying is provided. Also, 16
Is an exhaust passage through which one end communicates with the exhaust port 9 and the other end opens to the atmosphere to exhaust the exhaust gas from the working chamber 7,
The exhaust passage 16 has a catalyst device for purifying exhaust gas.
A silencer 18 is provided at each of 17 and the downstream thereof.

On the other hand, 20 is an air flow sensor disposed upstream of the throttle valve 14 in the intake passage 12 to detect the intake air amount, 21 is a throttle opening sensor that detects the engine load by the opening TVO of the throttle valve 14, and 22 is the exhaust passage 16 Is an O ₂ sensor arranged upstream of the catalyst device 17 for detecting the air-fuel ratio of the air-fuel mixture supplied to the working chamber 7 by the oxygen concentration component in the exhaust gas. Reference numeral 23 is a rotation speed sensor that detects the engine rotation speed, and 24 is a water temperature sensor that detects the engine cooling water temperature (engine temperature). Detection signals from these sensors 20 to 24 can be input to a control unit 25 including a CPU or the like as a control device for controlling the operation of the fuel injection valve 15.

Next, the operation of the control unit 25 will be described. In response to the signals from the sensors 20 to 24, the fuel injection valve 15 is controlled in accordance with the operating state of the engine. The thinning injection control is performed so that the combustion injection and the non-injection thereof are performed at a predetermined interval by the combustion injection valve 15 so that the combustion cycle and the rest cycle are repeated at a predetermined cycle. Specifically, this thinning-out injection control basically does not perform thinning-out injection during engine operation under high load as shown in FIG. 3 to FIG. 4 thinning, 1/3 thinning, and 1/2 thinning are performed to increase the thinning injection. Further, as shown in FIG. 3, the thinning rate is increased with respect to the engine rotation speed as the engine rotation speed decreases, and the acceleration (ΔTVO / Δ
For T), the thinning rate is increased as the acceleration becomes smaller as shown in FIG. 4. Regarding the engine load, engine speed, and acceleration, the thinning injection operation is not performed in the region where the output demand is high. While improving the output, the thinning rate is increased as the output demand becomes smaller to improve the fuel consumption. Further, as shown in FIG. 5, the thinning rate is increased as the engine warms up with respect to the engine temperature (engine cooling water temperature) to ensure combustion stability of the engine. Further, at the time of transition from the normal operation without thinning injection to the thinning injection operation, the thinning rate is not increased suddenly to a predetermined thinning rate as shown in FIG. This transition is performed smoothly without causing torque shock. On the contrary, when the thinning injection operation is changed to the normal operation, the thinning rate is gradually decreased so that the operation state without thinning injection can be achieved without torque shock.

As a feature of the present invention, during thinning injection operation in each working chamber 7 under the control of the control unit 25, as shown in FIG. And the combustion cycle and rest cycle
Since it is repeated at a ratio of 1: 1, since dilution gas is not carried in each combustion cycle, the air-fuel ratio of the air-fuel mixture supplied to each combustion cycle is set to lean. On the other hand, during operations such as 1/3 decimation operation and 1/4 decimation operation, where the decimation rate is less than 1/2, the combustion cycle is repeated multiple times, and then the pause cycle is performed. Is repeated at a ratio of 2: 1 or 3: 1. From this fact, in the combustion cycle after the previous combustion cycle among the combustion cycles, since the dilution gas from the previous combustion cycle was brought in, good ignition properties and combustibility were obtained even with this dilution gas. As the air-fuel ratio of the air-fuel mixture supplied to it is set to rich so that it can be obtained, in the combustion cycle after the previous rest cycle, since there is no carry-in of dilution gas as in the 1/2 thinning operation, it is supplied to it. The air-fuel ratio of the air-fuel mixture is set leaner than the air-fuel ratio in the combustion cycle after the previous combustion cycle.

Therefore, with the above thinning injection control, good ignitability and combustibility can be ensured even by bringing in the dilution gas in the combustion cycle after the previous combustion cycle, and the air-fuel ratio in the combustion cycle after the previous pause cycle can be secured. The fuel consumption can be reduced by the lean set, and it is possible to maintain both ignitability and combustibility and improve fuel consumption as a whole. In particular, in the rotary piston engine as in the above-described embodiment, since the amount of dilution gas originally brought in is large due to the overlap of the intake / exhaust ports 8 and 9, the above effect can be effectively exhibited, which is preferable.

The present invention can be applied not only to the rotary piston engine as in the above-described embodiment but also to a reciprocating engine and can achieve the same effect.

(Effects of the Invention) As described above, according to the fuel injection device of the thinned-out injection method of the present invention, during the thinned-out injection operation, the air-fuel ratio in the combustion cycle after the last rest cycle is compared with the combustion cycle after the last combustion cycle. Since the air-fuel ratio is set to be leaner than the air-fuel ratio, it is possible to effectively reduce fuel consumption while ensuring good ignitability and combustibility.

[Brief description of drawings]

1 shows an embodiment of the present invention, FIG. 1 is an overall schematic configuration diagram of a rotary piston engine, FIG. 2 is an explanatory view showing a thinning injection operation state in each working chamber, FIG. 3, FIG. 4 and FIG. FIG. 5 is a characteristic diagram of the engine speed, the acceleration, and the thinning rate at the engine temperature with respect to the engine load. 1 ... Rotary piston engine, 7 ... Working chamber, 15 ...
… Fuel injection valve, 25… Control unit.

Claims (1)

[Claims] 1. A fuel injection valve for injecting and supplying fuel, wherein fuel injection and non-injection are performed from the fuel injection valve so that a combustion cycle and a rest cycle are repeated in each combustion chamber at least during a low load operation. In an engine fuel injection device that performs and at predetermined intervals, the air-fuel ratio of the air-fuel mixture to be supplied to the combustion cycle after the last rest cycle should be leaner than the air-fuel ratio of the air-fuel mixture to be supplied to the combustion cycle after the last combustion cycle. A fuel injection device for an engine, comprising a control device for controlling the combustion injection valve.